Curently when we use filesystems we actually rely on kernel functionality to have persistence. Relying on syncing[1] can introduce interesting bugs. I can imagine a scenario where the FS has an API that is actually transactional and we can use that to transactionally mutate the content of files. instead of relying on fsync.

      1. fsync, fdatasync - synchronize a file's in-core state with
       storage device